Fluid delivery valve spring

ABSTRACT

A fuel injection pumping apparatus for supplying fuel to an internal combustion engine includes an injection pump which supplies fuel through a passage controlled by a delivery valve. Fuel flowing passed the delivery valve flows through a passage formed in a distributor member and which registers during a delivery stroke with an outlet. The return motion of the valve element of the delivery valve is achieved by means of a fluid spring which includes a plunger which is forced into a chamber during delivery of fuel by the injection pump. The fluid within the chamber is pressurised and when the delivery of fuel is complete the plunger bears against the valve element of the delivery valve to return the element to its original position.

United States Patent [191 [111 3,910,244

Skinner Oct. 7, 1975 [5 FLUID DELIVERY VALVE SPRING 3,046,905 7/1962Davis 123/139 BC Inventor: R be Thomas John S e High 3,738,576 6/1973 ONeill 239/533 wycombe England Primary ExaminerWendell E. Burns [73]Assignee: C.A.V. Limited, Birmingham, Assistant Examinr-James W.Cranson, Jr. England Attorney, Agent, or Firm-Holman & Stern [22] Filed:Apr. 9, 1974 Appl. No.: 459,345

Foreign Application Priority Data Apr. 26, 1973 United Kingdom 19820/73US. Cl 123/139 BC; l23/l39 R Int. Cl. F021) 5/00 Field of Search 123/139BC, 139 BE, 139 AM,

123/139 D, 139 R, 139 BD l8 lGct I4 [57] ABSTRACT A fuel injectionpumping apparatus for supplying fuel to an internal combustion engineincludes an injection pump which supplies fuel through a passagecontrolled by a delivery valve. Fuel flowing passed the delivery valveflows through a passage formed in a distributor member and whichregisters during a delivery stroke with an outlet. The return motion ofthe valve element of the delivery valve is achieved by means of a fluidspring which includes a plunger which is forced into a chamber duringdelivery of fuel by the injection pump. The fluid within thechamber ispressurised and when the delivery of fuel is complete the plunger bearsagainst the valve element of the delivery valve to return the element toits original position.

7 Claims, 1 Drawing Figure U.S. Patent Oct. 7,1975

FLUID DELIVERY VALVE SPRING This invention relates to liquidfuel pumpingapparatus for supplying fuel to internal combustion engines and of thekind comprising in combination, an injection pump, a distributor memberrotatable in a body part, the injection pump and distributor memberbeing adapted to be driven in timed relationship with an associatedengine, the distributor member including a passage communicating withthe pumping charn ber of the injection pump,' and said passageregistering in -turn during successive delivery strokes of the injectionpump, with outlet port s formedin' the body part and which in use,communicate respectively with the injection nozzles of an associatedengineaand a delivery valve in said passage, said delivery valve openingduring the delivery of fuel by the injection pump.

The object of the invention is to provide such an apparatus in a simpleand convenient form.

According to the invention, in an apparatus of the kind specified, saiddelivery valve comprises a valve element movable to an open position bythe pressure of fuel developed by the injection pump, and a fluid springagainst the force exerted by which the valve element moves to the openposition, said fluid spring acting in part to effect movement of thevalve element to its closed position.

According to a further feature of the invention, said fluid spring ischarged with fuel during the delivery strokes of the injection pump, anon-return valve being provided to trap the fuel under pressure.

One example of a fuel pumping apparatus in accordance with the inventionwill now be described with reference to the accompanying drawing whichshows a sectional side elevation of a portion of the apparatus.

Referring to the drawing, there is provided a body part in which ismounted a rotary cylindrical distributor member 11. Also provided is aninjection pump 12 and the injection pump and distributor member 11 areadapted to be driven in timed relationship with an engine with which theapparatus is associated. In practice, the injection pump comprises apair of reciprocable pumping plungers which are accommodated within atransversely extending bore formed in the distributor member.Surrounding the distributor member is an annular cam ring on theinternal peripheral surface of which is formed a plurality of pairs ofinwardly extending cam lobes. Interposed between the internal surface ofthe cam ring and the plungers are rollers respectively which are mountedupon shoes. As the distributor member rotates, inward movement will beimparted to the plungers, such inward movement occurring during thedelivery stroke of the injection pump.

The pumping chamber of the injection pump communicates with a passage 13formed in the distributor member, and which communicates with a radiallyextending passage 14. The radially extending passage breaks out onto theperiphery of the distributor memher, and is positioned to register inturn, and during successive delivery strokes of the injection pump, witha plurality of outlet ports 15 formed in the body part. The outlet portsin use, are connected respectively to injection nozzles 16 of theassociated engine.

The apparatus also includes a feed pump not shown which supplies fuel tothe injection pump during the filling strokes thereof, the amount offuel supplied to the injection pump being controlled by throttling meansnotshown. j The apparatus also includes a delivery valve generallyindicated at 16a and this includesja cylindrical valve element 17whichis slidably located within an enlargement 18.0f the passage 13, Thevalve element 17 has a plurality of flats formed on its peripheralsurface, and which extend to a tapered portion of the element. In theclosed position of the delivery valve, the flats are not exposed beyondthe end of the enlarged portion 18, but during delivery of fuel by theinjection pump, the valve element is moved axially the flats becomeexposed. beyond the portion 18 thereby to permit fuel to flow from thepassage 13 to the passage l4, and a passage 15 to therespectiveinjection nozzle.

There is: also provided a plunger 19 which bears against the valveelement 17, the plunger 19 extends through a bore formed in a plug 20and within which is defined a chamber 21. Mounted within the chamber 21is a stop member 22, which is engageable by the plunger 19 to limit theextent of movement of the plunger and also the valve element 17.

The chamber 21 is in communication with the passage 14 by way of anon-return valve 23 which comprises a ball which can co-operate with aseating defined in a passage communicating with the chamber andextending substantially at right angles to the bore in which the plungeris mounted. The valve acts to prevent loss of-pressure within thechamber 21 and the extent of movement of the ball away from the seatingis determined by means of the plunger 19. In use, the chamber 21 becomescharged with fuel under pressure from the passage 14, this fuel beingsupplied by the injection pump. The pressure is retained within thechamber 21 by the valve 23, and this pressure acts upon the plunger toassist movement of the valve element 17 towards the closed position asis shown in the drawing. The chamber 21 and in particular the fuelpressure within it, together with the plunger 19 constitute a fluidspring which replaces the more conventional form of coiled compressionspring which has been used hithertofore and which is subject to limita'tions of design due to stress and frequency considerations.

It will be noted that the flats are only uncovered after a predeterminedmovement of the valve element 17, and during closure of the valveelement relief of fuel under pressure in the passage 14 and thecommunicating outlet 15 together with the fuel in the pipe lineinterconnecting the outlet 15 with the injection nozzle 16, occurs. Ifdesired, the outlets 15 may be provided with pressurising valves, thepurpose of which is to minimise the risk of cavities forming within theoutlets 15 and passage 14.

I claim:

1. A liquid fuel pumping apparatus comprising an injection pump, adistributor member rotatable in a body part, the injection pump anddistributor member being driven in timed relationship, the distributormember including a passage communicating with the injection pump, andsaid passage registering in turn during successive delivery strokes ofthe injection pump, with outlet ports formed in the body part, and adelivery valve in said passage, said delivery valve opening during thedelivery of fuel by the injection pump, said delivery valve comprising avalve element movable to an open position by the pressure of fueldeveloped by the injection pump, and a fluid spring against the forceexerted by which the valve element moves to the open position, saidfluid spring acting in part to effect movement of the valve element toits closed position.

2. An apparatus as claimed in claim 1 including passage means throughwhich said fluid spring is charged with fuel during the delivery strokesof the injection pump, and a non-return valve in said passage means totrap the fuel under pressure.

3. An apparatus as claimed in claim 1 in which the fluid spring includesa plunger for engagement by the valve element, said plunger enteringinto a chamber containing fuel, and passage means through which thechamber is charged with fuel during a delivery stroke of the injectionpump.

4. An apparatus as claimed in claim 3 including a non-return valve insaid passage means operable to trap stop located in the chamber andacting to limit the extent of movement of the plunger and the valveelement.

7. An apparatus as claimed in claim 6 in which the non-return valvecomprises a ball located within the chamber the ball co-operating with aseating defined in a passage extending out of said chamber substantiallyat right angles to the bore, the plunger acting to limit the movement ofthe ball away from the seating'

1. A liquid fuel pumping apparatus comprising an injection pump, adistributor member rotatable in a body part, the injection pump anddistributor member being driven in timed relationship, the distributormember including a passage communicating with the injection pump, andsaid passage registering in turn during successive delivery strokes ofthe injection pump, with outlet ports formed in the body part, and adelivery valve in said passage, said delivery valve opening during thedelivery of fuel by the injection pump, said delivery valve comprising avalve element movable to an open position by the pressure of fueldeveloped by the injection pump, and a fluid spring against the forceexerted by which the valve element moves to the open position, saidfluid spring acting in part to effect movement of the valve element toits closed position.
 2. An apparatus as claimed in claim 1 includingpassage means through which said fluid spring is charged with fuelduring the delivery strokes of the injection pump, and a non-returnvalve in said passage means to trap the fuel under pressure.
 3. Anapparatus as claimed in claim 1 in which the fluid spring includes aplunger for engagement by the valve element, said plunger entering intoa chamber containing fuel, and passage means through which the chamberis charged with fuel during a delivery stroke of the injection pump. 4.An apparatus as claimed in claim 3 including a non-return valve in saidpassage means operable to trap fuel under pressure within said chamber.5. An apparatus as claimed in claim 4 in which said chamber is definedwithin a plug which can be mounted in a recess defined in thedistributor member, said plunger being located within a bore defined insaid plug and communicating with said chamber.
 6. An apparatus asclaimed in claim 5 including a stop located in the chamber and acting tolimit the extent of movement of the plunger and the valve element.
 7. Anapparatus as claimed in claim 6 in which the non-return valve comprisesa ball located within the chamber the ball co-operating with a seatingdefined in a passage extending out of said chamber substantially atright angles to the bore, the plunger acting to limit the movement ofthe ball away from the seating.